Propargyl carbonates catechol

This type of reactivity has been exploited for the preparation of 1,4-benzodioxanes from catechols and propargylic carbonates. Using 2,2 -bis(diphenylphosphino)-l,T-binapthyl (BINAP), this process has been rendered asymmetric with ee s up to 97% (Equation (68)).254,255... 

Sinou et al. reported that the palladium-catalyzed condensation of catechol 679 with various propargylic carbonates 678 gave the 2,3-dihydro-2-ylidene-l,4-benzodioxins 680.286 The reaction using (R)-BINAP as a chiral ligand gave the products 680 in high yields with high ee values (Scheme 210). 

Substitution reactions of attylic systems. An access to allylic thiols is based on substitution by MeCOSK with (dbaljPdj-dppb as catalyst. 2-Alkylidene-3-alkyl-l,4-benzodioxanes are readily formed in a reaction between catechols and propargylic carbonates. ... 

Dihydro-l,4-benzodioxines 139 and 140 are prepared by the reaction of propargyl carbonates 136 with catechol (137) by attacking either terminus of the TT-allylpalladium intermediate 138. 

The reaction of propargyl carbonate (141) with catechol (137) using DPPB gave 2-methylenebenzodioxin 142. The reaction of methyl-substituted alkynyl carbonate 143 with 137 afforded 3-methylbenzodioxin 144, and a mixture of 146 and 147 was obtained from 145 in a ratio of 22 78 [41]. 

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